The list of customer relationship management and human resources software companies peeved at LinkedIn over API access is growing at a rapid clip.

LinkedIn changed its application programming interface policies last August to mandate that any software used for hiring, marketing or sales must be a developer partner. Now LinkedIn appears to be enforcing the changes more aggressively.

We are unhappy to announce the discontinuation of the LinkedIn integration with Zoho CRM immediately. The latest changes in LinkedIn’s Developer API agreement do not allow us to offer this integration to customers any more without strategic partnership. In the past few months, we have been trying our best to convince the team at LinkedIn but we have been unsuccessful. Recently, we received this notice from the LinkedIn API review team:

LinkedIn prioritizes whom we partner with based on strategic alignment, size of opportunity, and current needs. At this time we do not believe your product would add enough sufficient value beyond our existing products to warrant a partnership. However, given the dynamic nature of our industry, we are continuously evaluating our partnership criteria and potential partners.

LinkedIn's partner page seems to indicate that it's done vetting the CRM universe and fine with Salesforce and Microsoft as partners. There's no "apply now" button under CRM.

Zoho added that it'll focus on working with Facebook and Twitter for CRM profiles.

Does LinkedIn care? From a business standpoint probably not. LinkedIn can mine its own data for profits and owns a fine business based social graph. There are more returns if LinkedIn puts a wall around its data---at least in the short term.

In the long run, LinkedIn's API rules are off the mark. By closing out its data, a long list of social CRM companies are likely to simply come up with something else. Facebook also has data on the same folks on LinkedIn and could do a business version quickly if it really wanted to.

LinkedIn's API rules that have a few CRM vendors miffed.

Zoho said "we will continue to explore the possibilities of strengthening our integration with social platforms, like Facebook, Twitter and others." Let's say enough LinkedOut software vendors do the same thing. Eventually, there's a LinkedIn workaround created.

LinkedIn can do what it wants, but the API game can bite back especially if the company is only going to work with two CRM vendors. After all, it's not like companies like Oracle and SAP---two CRM players not on LinkedIn's partner list---are small fries.

And if you zoom out LinkedIn's partner program may be lacking overall. Under mobile, LinkedIn lists the following device manufacturers as partners: HTC, Microsoft, RIM, Sony. All are struggling.

Update: LinkedIn said it has partnered with Apple and Samsung, but they aren't listed.